For the construction of wall assemblies, the moisture levels within the wall cavity can be controlled to avoid the formation of mold, which can lead to structural damage and health consequences. An interior smart vapor barrier can be placed on the inner side of an exterior wall cavity to control moisture vapor transmission between the air in the house and the air in the wall cavity. This type of vapor barrier is often called a smart barrier, because it has an increased moisture vapor permeability with increased humidity: during the winter and heating season, when the relative humidity within the wall cavity is low, the interior barrier can maintain the low moisture levels within the wall cavity, while during summer, in the cooling season, when the relative humidity within the wall cavity is high, the smart barrier allows the moisture to escape into the house.
The above-described interior barrier layer is however not suitable as an exterior barrier layer facing the outdoor environment, because different moisture and temperature conditions apply on the exterior surface of a wall. There is a need for further improving exterior weather resistant barriers.